The invention relates to batteries.
Batteries, such as alkaline batteries, are commonly used as energy sources. Generally, alkaline batteries have a cathode, an anode, a separator and an electrolytic solution. The cathode is typically formed of an active material (e.g., manganese dioxide), carbon particles and a binder. The anode can be formed of gel including an active material (e.g., zinc particles). The separator is usually disposed between the cathode and the anode. The electrolytic solution, which is dispersed throughout the battery, can be a hydroxide solution.
It can be desirable for a battery to provide high energy output at a high rate. Generally, such a battery is designed by increasing the surface area of active cathode material (e.g., manganese dioxide) in contact with the electrolytic solution. The surface area of the active cathode material in contact with the electrolytic solution can be increased by increasing the porosity of the active cathode material. The porosity of the cathode can be increased by decreasing the amount of active material in the cathode. As a result, in batteries designed to provide a high energy output at a high rate, the ratio of the mass of the active cathode material to cathode volume is relatively low.
The invention relates to batteries that have a cathode with a relatively high ratio of manganese dioxide to cathode volume and that can provide high energy output at a high rate when intermittently subjected to a high energy load. The batteries are not limited by their size (e.g., AA, AAA, AAAA, C or D), but a battery""s high rate performance and ratio of manganese dioxide to cathode volume generally vary depending upon the size of the battery.
In one aspect, the invention features a battery, preferably a AA battery, that includes a cathode, an anode and a separator disposed between the anode and the cathode. The cathode contains at least 2.8 grams of manganese dioxide per cubic centimeter of cathode volume. The battery takes at least 1.6 hours to discharge to 1.1 Volts according to the pulsed test.
As used herein, xe2x80x9cthe pulsed testxe2x80x9d refers to a test in which a battery is discharged from its open circuit voltage to a particular final voltage at a rate that alternates between 1 Watt (3 second pulses) and 0.1 Watt (7 second pulses).
In another aspect, the invention features a battery, preferably a AA battery, that-includes a cathode, an anode and a separator disposed between the anode and the cathode. The cathode contains at least 2.8 grams of manganese dioxide per cubic centimeter of cathode volume. The battery takes at least 2.85 hours to discharge to 0.9 Volts according to the pulsed test.
In a further aspect, the invention features a battery, preferably a AAA battery, that includes a cathode, an anode and a separator disposed between the anode and the cathode. The cathode contains at least 2.85 grams of manganese dioxide per cubic centimeter of cathode volume. The battery takes at least 0.5 hours to discharge to 1.1 Volts according to the pulsed test.
In another aspect, the invention features a battery, preferably a AAA battery, that includes a cathode, an anode and a separator disposed between the anode and the cathode.
The cathode contains at least 2.85 grams of manganese dioxide per cubic centimeter of cathode volume. The battery takes at least 0.8 hours to discharge to 0.9 Volts according to the pulsed test.
The batteries can have a relatively large inner cathode diameter, a relatively large inner volume, a relatively low ratio of zinc to electrolytic solution and/or a relatively low porosity.